<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>盒子模型演示</title>
    <style>
        .wai{
            border: 1px solid red;
            width: 200px;
            height: 200px;

            /*设置内边距,会导致外框的变化*/
            /*padding: 50px;*/
        }

        .nei{
            border: 1px solid blue;
            width: 100px;
            height: 100px;

            /*设置外边距*/
            /*margin-top: 50px;
            margin-left: 50px;
            margin-right: 50px;
            margin-bottom: 50px;*/

            /*margin: 50px;*/

            /*上、右、下、左*/
            /*margin: 70px 35px 30px 65px;*/
        }
    </style>
</head>
<body>
    <div class="wai">
        <div class="nei">

        </div>
    </div>
</body>
</html>